class_docstr: MetricsLogger collects metrics measured during experiments.
  
  MetricsLogger is the (only) part of the Metrics API.
  An instance of the class should be created for the Run class, such that the
  log_scalar_metric method is accessible from running experiments using
  _run.metrics.log_scalar_metric.
code: def __init__(self):
      # Create a message queue that remembers
      # calls of the log_scalar_metric
      self._logged_metrics = Queue()
      self._metric_step_counter = {}
      """Remembers the last number of each metric."""
  
file_path: sacred/sacred/metrics_logger.py
imports: import datetime
  import sacred.optional
  from queue import Queue, Empty
label_desc: Use image node_id 1 to create a new MetricsLogger object  with example: obj = MetricsLogger()